Chapter 1: A First Program Using C# · Programming •Computer program –A set of instructions that tells a computer what to do –Also called software •Software comes in two broad

Chapter 1:

A First Program Using C#

Programming

• Computer program

– A set of instructions that tells a computer what to do

– Also called software

• Software comes in two broad categories

– System software

– Application software

• Machine language

– Expressed as a series of 1s and 0s • 1s represent switches that are on, and 0s represent switches that

are off

2 Microsoft Visual C# 2012, Fifth Edition

Microsoft Visual C# 2012, Fifth Edition

Programming (cont’d.)

• Part of the HelloWorld Program in machine language

3


• High-level programming language

– Uses reasonable terms such as “read,” “write,” or “add” instead of the sequence of on/off switches that perform these tasks

– Allows you to assign reasonable names to areas of computer memory

– Has its own syntax (rules of the language)

• Compiler

– Translates high-level language statements into machine language



• Programming logic

– Involves executing the various statements and procedures in the correct order to produce the desired results

• Debugging

– The process of removing all syntax and logical errors from the program

– Syntax errors are discovered through compilation

– Logical errors are discovered through testing


Features of Object-Oriented Programming Languages

• Class

– A category of objects or a type of object

– Describes the attributes and behaviors of every object that is an instance, or object, of that class

• Object

– An instance of a class

– Contains its own set of attribute values


The C# Programming Language

• Developed as an object-oriented and component-oriented language

• Part of Microsoft Visual Studio 2012

• Allows every piece of data to be treated as an object and to consistently employ the principles of object-oriented programming

• Contains a GUI interface that makes it similar to Visual Basic


The C# Programming Language (cont’d.)

• Modeled after the C++ programming language

– However, eliminates some of the most difficult features to understand in C++

• Very similar to Java

– In C#, simple data types are objects


Writing a C# Program that Produces Output

literal string

argument method

class

namespace


Writing a C# Program that Produces Output (cont’d.)

• Namespace

– Provides a way to group similar classes

– Can be used to avoid naming conflicts in large projects

• C# method parts

– Method header • Includes the method name and information about what will pass

into and be returned from a method

– Method body • Contained within a pair of curly braces and includes all the

instructions executed by the method



• Access modifier

– Defines the circumstances under which the method can be accessed

– Public, private, protected, internal



• Keywords

– Predefined and reserved identifiers that have special meaning to the compiler

• The name of the method is Main()

– Every application must have a Main() method

– Classes with a Main() method are called application classes; others are non-application classes

• The method returns nothing as indicated by the keyword void


Selecting Identifiers

• Requirements

– Must begin with an underscore, an at sign (@), or a letter • Letters include foreign-alphabet letters

– Can contain only letters, digits, underscores, and the at (@) sign • Not special characters such as #, $, or &

– Cannot be a C# reserved keyword



Selecting Identifiers (cont’d.)






Adding Program Comments

• Program comments

– Nonexecuting statements that document a program

• Comment out

– Turn a statement into a comment

• Types of comments in C#

– Line comments

– Block comments


Adding Program Comments (cont’d.)


Using the System Namespace


Using the System Namespace (cont’d.)


Compiling and Executing a C# Program

• Steps for viewing a program’s output

– Compile source code into intermediate language (IL)

– The C# just in time (JIT) compiler translates the intermediate code into executable statements

• You can use either of two ways to compile

– The command line

– The Integrated Development Environment (IDE)


Compiling Code from the Command Prompt

• Example of an operating system error message – Command csc stands for “C Sharp compiler”

– Location of csc.exe c:\Windows\Microsoft.NET\Framework\vX.X.XXX


Compiling Code from the Command Prompt (cont’d.)

• Example of a command line generated error message

– Program error messages start with the program name followed by the line number and position within the line of the error


Compiling Code Using the Visual Studio IDE

• Advantages of using the Visual Studio IDE

– Some of the code you need is already created for you— auto-complete

– The code is displayed in color

– Some syntax errors are caught as you type

– You can double-click an error message and the cursor will move to the line of code that contains the error

– Other debugging tools are available


Compiling Code Using the Visual Studio IDE (cont’d.)


Deciding Which Environment to Use

• Advantage of using the command line

– Saves disk space

• Advantages of using the Visual Studio IDE

– Automatic sentence completion

– Words are displayed using different colors based on their category

– The code automatically generated by the IDE is very helpful when writing a GUI


You Do It (cont’d.)

Compiling and Executing a Program Using the Visual Studio IDE

• Steps

– Create a new project (console application)

– Enter the project name

– Write your program using the editor

– To compile the program, click Build on the menu bar, and then click Build Solution • As an alternative, you can press F6

– Click Debug on the menu bar and then click Start Without Debugging





Compiling and Executing a Program Using the Visual Studio IDE (cont’d.)


Adding Comments to a Program

• Line comment example // Filename Hello.cs

// Written by <your name>

// Written on <today’s date>

• Block comment example /* This program demonstrates the use of

the WriteLine() method to print the

message Hello, world! */



Documents

Chapter 1: A First Program Using C# · Programming •Computer program –A set of instructions that tells a computer what to do –Also called software •Software comes in two broad